LAKE ANDES, S.D. — People living near Svatos Bay south of Lake Andes in far southeastern South Dakota have been dealing with a foul stench this past week due to a litany of dead carp piled up along the shoreline.
While several locals said it’s not uncommon for a few fish carcasses to wash up on the shore during the summer months, Lake Andes resident Steve Petry hasn’t witnessed this many dead carp along the bay in his 17 years of owning a nearby property.
“I think the cause is something natural, because there are no catfish, bass or walleye in the water from what I and others have seen,” Petry said Friday, June 21. “The water level was so high before the dam was released, and now there is some dead grass rotting. I think this has made for a lack of food for fish as well.”
Among the causes Petry is mulling over, he suspects the warmer temperatures paired with shallow water levels after the release of the Fort Randall Dam — which is roughly 3 miles downstream from Svatos Bay — are major factors for the dead carp scattered around the bay.
Petry believes the flooding Lake Andes has experienced this summer has caused some vegetation in the water to die, which in turn has had an impact on the oxygen levels in the water.
Carp are a common species of freshwater fish that live in the Missouri River and nearby lakes. Carp are known as bottom feeders, and they eat a variety of insects, algae and plant matter.
Petry said he’s also heard reports of dead carp surfacing upstream toward Lake Andes, leading to his speculation that the majority of the fish are coming from Lake Andes. The flooding of Lake Andes has also impacted Petry’s fishing, as he regularly catches catfish and a few bass out of the Svatos Bay area.
“I don’t believe it’s something such as toxic water, because I’ve heard a lot of dead carp are floating around upstream. I think there aren’t many good game fish left in Lake Andes after the flood as well, and the dead carp are traveling through the water,” Petry said. “I haven’t been able to fish for catfish and bass like I have years prior.”
The area where the dead fish are piling up at Svatos Bay includes two culverts, which allow a passage for water to flow downstream and into the Missouri River. While some of the decaying fish are located on the north side of the culverts where water is more shallow, there are nearly as many lying around the south side of the culvert, where the water levels are a bit deeper.
Jeff Martin, a wildlife conservationist for the South Dakota Game, Fish & Parks in Charles Mix County, said the volume of dead carp at Svatos Bay recently caught the GF&P’s attention, prompting Martin to monitor the situation.
While Martin reiterated the frequency of small amounts of dead carp washing up on the Svatos Bay shorelines during the early half of summer, he pointed to the unique flooding of Lake Andes — which is just 3 miles upstream — as a potential root cause.
“A lot of those dead fish have come 2 to 3 miles out of the flooded Lake Andes, and it appears to be all carp,” Martin said. “There may be some water quality sampling along the areas where the dead carp have been surfacing, but it’s nothing too alarming. We’re monitoring it.”
Martin said the shallow waters that surround the area where the fish carcasses are piling up has seen a significant drop in water levels due to the recent release of the Fort Randall Dam. Dropping from roughly 15 feet to 8 feet, Martin said the reduced water level hasn’t affected fishes ability to swim through the shallow water. However, Martin said the dam release hasn’t lowered the water level enough to trap fish from swimming downstream.
“The dam has been releasing pretty heavy for two to three weeks now, so the water has been coming down nice and steady. It’s not been a massive drop where fish get trapped, but I believe this could be related to the Lake Andes flooding effects,” Martin said. “I can’t say for sure, but I’m looking into it.”